The present invention pertains generally to ultrasonic probes and, more particularly, to an improved ultrasonic probe tip which emulsified and more efficiently removes tissue as it is aspirated through the tip.
Until the late 1960's, ophthalmological surgical techiques for cataract removal were performed using standard intracapsular cataract extraction techniques which, although generally satisfactory, require a prolonged recovery time of up to several months. Since that time, a procedure known as phacoemulsification, or use of an ultrasonic probe to break up and remove cataracts, has become widely used because it offers a remarkable decrease in recovery time. Indeed, a patient can sometimes return to work the day after surgery with this new technique.
The procedure for removal of cataract tissue is described in the article entitled "History of Emulsification and Aspiration of Senile Cataracts," by Charles D. Kelman, appearing in Transactions American Academy of Ophthalmology and Otolaryngology, Volume 78, January-February, 1974, pp. OP5-13 (originally presented at the 78th Annual Meeting of the American Academy of Ophthalmology and Otolaryngology, Dallas, Tex., Sept. 16-20, 1973). Generally speaking, a tip in the form of a hollow tube is inserted into the anterior chamber of the eye through a small incision into contact with the cataract tissue. The tip is vibrated by a hand held probe at an ultrasonic rate, and hydrodynamic flow of a saline solution is estabilished in order to prevent collapse of the anterior chamber. As particles of the cataract tissue are cut from the cataract mass, the particles are removed from the chamber through the tip of the ultrasonic probe. In the case of hard cataracts, these particles, which have a tendency to slide into contact with the walls of the chamber, have an abrasive character. Since certain portions of the eye including the chamber walls are very prone to abrasion sensitivity, the cataract particles must be quickly, and as completely as possible, removed from the chamber. This is done by aspiration through the hollow tip.
During aspiration of cataract tissue, the tip of the ultrasonic probe must be very carefully manipulated under the field of view of a microscope in order to prevent aspirating other than cataract tissue and to insure that all the cataract particles are removed from the chamber. Close control of the tip is especially critical at the peripheral regions of the cataract. The tip must be able to efficiently remove the cataract tissue without clogging or otherwise hindering the surgical procedure.
Several improved ultrasonic probes have been developed for performing this and other delicate types of surgery as well as cleaning of teeth and the like. These probes generally also consist of a tip for cutting/cleaning material at the operation site, a hand piece for mounting the tip and associated circuitry, and a pieoelectric crystal or other means for supplying ultrasonic energy to vibrate the tip. My prior design disclosed in U.S. Pat. No. 4,169,984, is one of the most innovative, greatly improving the ultrasonic handpiece capable of use with a variety of tips for removing cataract tissue, cleaning and similar functions. While remarkable advances have thus been made in the total instrument and the technique of use, the basic design of the tips has remained unchanged over the years. U.S. Pat. No. 4,428,748 to Peyman et al., issued in 1984, is typical of the attempts that have been made to modify the probe tip. In this instance an additional drive mechanism is required in an attempt to provided better cutting action. However, even with this expensive modification, such designs, like other prior art inventions that I am aware of, are hampered by slow cutting action, clogging and generally unsatisfactory performance.
To put it another way, prior ultrasonic probe tips have not proved to be as effective and efficient in removing the undesired tissue as they could be. The cutting edge of the probe tip often shears large pieces of cataract tissue which cannot easily be aspirated with the smal diameter tip. These particles tend to either not be aspirated and, therefore, left in the eye to damage walls of the eye, or, as is often the case, clog the tip and prevent aspiration of the particles. If the tip clogs, surgery must be halted to clean or change the tip. The delay in surgery increases the trauma and risk to the patient. A new and improved ultrasonic probe tip which can efficiently remove severed tissue, emulsify the tissue into fine particles and avoid the surgical delays caused by tip clogging is, therefore, needed.
Accordingly, one object of the invention is to provide a new and improved probe tip for ultrasonically removing tissue.
A further object of the present invention is to provide a new and improved ultrasonic probe tip which will not clog during the surgical procedure.
Another object of the invention is to provide a new and improved ultrasonic probe tip for performing phacoemulsification for cataract removal.
Still another object of the invention is to provide a new improved and low cost probe tip and method for performing cataract particles are phacoemulsification wherein cataract particles are efficiently aspirated from the anterior chamber to avoid damage to delicate eye tissue.